1. Field of the Invention
The present invention relates to a screw insert, and more particularly, to an insert for receiving a bone screw to increase the anchoring strength of the bone screw.
2. Description of Related Art
A variety of devices are known in the art for anchoring surgical components to bones. Of such devices, many are directed to bone screws for attaching bones together or to attaching prostheses to bones. There are several uses for bone screws in treating spinal conditions, treating joints, and anchoring sutures to bones, among others.
Typically, when a bone screw is implemented to treat a bone condition, a drill is used to bore into the bone. The resulting bore typically extends through cortical bone and into cancellous bone. After the bore is formed, a bone screw can be driven into the bore with the threads engaging the bone where possible. Various items can then be anchored to the bone by means of the bone screw in place within the bore.
The anchoring strength of bone screws as described above is limited. Anchoring strength can be limited by defects in the bone. For example, osteoporotic bone in older patients is much weaker than bone in young, healthy patients. Errors in the placement of the bore can also compromise the anchoring strength of bone screws. For example, current orthopedic devices used in the spine rely on screws inserted directly into the vertebral structure. Fixation strength is highly dependent not only on strength and integrity of the bone, but also on the placement of the bores. This is a significant limitation for spinal devices, especially those aimed at non-fusion applications such as dynamic stabilization devices. Placement and insertion of bores and screws is often difficult in bony structures such as the pedicle or facet. An alignment mistake can lead to the bore lying too close to or breaking through the cortex on one side of the bone structure. When a bone is compromised in this manner, it may provide inadequate load distribution for use of a conventional bone screw.
Conventional methods and systems of anchoring structures to bones generally have been considered satisfactory for their intended purpose. However, there remains an ever present need to advance the state of the art for increasing the anchoring strength of structures like bone screws. There also remains a need in the art for a method and a system that can increase the anchoring strength of bone screws in defective bone tissue or compromised bores. The present invention provides a solution for these problems.